SNP Optimizer not adhering to Fixed Lot Size

Hi Experts,

I am facing a problem of optimizer not respecting the fixed lot size defined in product master. Explanation is as follows

Product 'A' must be produced in a fixed lot of 5 tons. I have maintained the same in Lot size tab of product master. I am using discrete optimizer with Minimum PPM/PDS Lot Size & Integral Lot Size both enabled in the optimizer profile. I have also enabled the discretization in the PPM.

Now if the demand is 17 tons, the expected output is to have 4 orders of 5 tons each. However system is creating 3 orders of 5 tons & the last order of 2 tons to cover the demand of 17 tons. I have maintained storage cost for the product. If I don't maintain this, then the system plans much more quantities than the requirement.